1. Field of the Invention
The present invention generally relates to a band pass filter, and particularly to a band pass filter that can be formed in a multi-layered circuit substrate.
2. Description of Related Art
With development in technology, wireless communication systems, such as, cordless phones, cell phones, Bluetooth, wireless local area networks (WLAN), are being increasingly popularized. Most of such wireless communication systems employ a band pass filter to reduce noise while passing desired signals. In some existing systems, the band pass filter is typically disposed in a multi-layered low temperature co-fired ceramic (LTCC) substrate. However, this requires a high cost for fabricating the LTCC substrate. In addition, the band pass filter disposed in the LTCC substrate needs to be separately mounted to the circuit substrate by a surface mount technology (SMT) and occupies a certain surface area of the circuit substrate.